• Title/Summary/Keyword: Axisymmetric

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Analysis for the Non-axisymmetric mode of Annular type Piezoelectric Actuator (환상형 압전진동자의 비축대칭 모드에 관한 해석)

  • 박순종
    • Proceedings of the Acoustical Society of Korea Conference
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    • pp.9-12
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    • 1996
  • This paper introduces an analysis of the non-axisymmetric mode due to in-plane vibration of an annular type piezoelectric actuator using FEM(Finite Element Method). The actuator is used as stator of ultrasonec motor. The freqrency charecterisrics and non-axisymmetric mode of the annular piezoelectric acruator are considered at a steady-state condition. The non-axisymmetric mode is occured by two sinusodial voltage sources with $\pi$/2 phase difference on the time domain. The resonant frequency of non-axisymmetric of non-axisymmetric mode is 60.358 kHz and 59.880 kHz for calculation and measurement, respectivly. The error was 0.8% between calculation and measurement. The revolution of the non-axisymmetric mode for actuator is analized at a period of exciting voltage sources using annimation. It is confirmed that the actuator has an usefulness as the stator of ultrasonic motor and the preposed method has a properity.

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Stress intensity factors for 3-D axisymmetric bodies containing cracks by p-version of F.E.M.

  • Woo, Kwang S.;Jung, Woo S.
    • Structural Engineering and Mechanics
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    • v.2 no.3
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    • pp.245-256
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    • 1994
  • A new axisymmetric crack model is proposed on the basis of p-version of the finite element method limited to theory of small scale yielding. To this end, axisymmetric stress element is formulated by integrals of Legendre polynomial which has hierarchical nature and orthogonality relationship. The virtual crack extension method has been adopted to calculate the stress intensity factors for 3-D axisymmetric cracked bodies where the potential energy change as a function of position along the crack front is calculated. The sensitivity with respect to the aspect ratio and Poisson locking has been tested to ascertain the robustness of p-version axisymmetric element. Also, the limit value that is an exact solution obtained by FEM when degree of freedom is infinite can be estimated using the extrapolation equation based on error prediction in energy norm. Numerical examples of thick-walled cylinder, axisymmetric crack in a round bar and internal part-thorough cracked pipes are tested with high precision.

Hydroforming of a Non-axisymmetric Thin-walled Tubular Component with Variable Cross Sections (가변 단면을 가지는 비대칭 얇은 관 부품의 액압성형 연구)

  • Kang, H.S.;Joo, B.D.;Hwang, T.W.;Moon, Y.H.
    • Transactions of Materials Processing
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    • v.24 no.5
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    • pp.368-374
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    • 2015
  • Hydroforming of a non-axisymmetric thin-walled tubular component with variable cross sections was analyzed. In order to solve the sealing problem which occurred due to the thin and non-axisymmetric shape, the use of a lead patch on the punch, which had been successful in hydroforming of thin tubes, was evaluated. A lead patch was attached to the punch to solve the sealing problem, which was caused by the stress gradient in the non-axisymmetric shape. FEM and experiments were also performed to analyze these sealing problems associated with the punch shape and non-axisymmetric shape. Finally, the lead patch was attached at tube surface where intensive local strain concentration would occur to enhance the hydroformability. These methods were successfully used to fabricate non-axisymmetric thin-walled tubular component with variable cross sections that had previously failed during traditional hydroforming.

Development on the Automated Process System for Cold Forging of Non-axisymmetric Parts (비축대칭 제품의 냉간단조 공정설계 시스템 개발)

  • 이봉규;조해용;권혁홍
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.527-530
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    • 1997
  • An automated process planning system for cold forging of non-axisymmetric parts of comparatively simple shape was developed in this study. Programs for the system have been written with Visual LISP in the AutoCAD using a personal computer and are composed of four main modules such as input module, shape cognition and shape expression module, material diameter determination module and process planning module. The design rules and knowledges for th system are extracted from the plasticity theories. handbook, relevant reference and empirical knowledge of field experts. Generally, in forging, only front view is needed for expression of axisymmetric parts, but non-axisymmetric parts are needed both front view and plane. At the plane, this system cognizes the external shape of non-axisymmetric parts - number of sides of regular polygon and radius of a circle circumscribing the polygon of n sides. At the front view, the system perceives diameter of axisymmetric portions and hight of primitive geometries such as polygon, cylinder, cone, concave, convex, etc.

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Non-axisymmetric dynamic response of imperfectly bonded buried orthotropic pipelines

  • Dwivedi, J.P.;Mishra, B.K.;Upadhyay, P.C.
    • Structural Engineering and Mechanics
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    • v.6 no.3
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    • pp.291-304
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    • 1998
  • This paper deals with the non-axisymmetric dynamic response of an imperfectly bonded buried orthotropic pipeline subjected to longitudinal wave (P-wave) excitation. An infinite cylindrical shell model, including the rotary inertia and shear deformation effects, has been used for the pipeline. For some cases comparison of axisymmetric and non-axisymmetric responses have also been furnished.

Axisymmetric Modeling of Dome Tendons in Nuclear Containment Building II. Verification through Numerical Examples (원전 격납건물 돔 텐던의 축대칭 모델링 기법 II. 수치예제를 통한 검증)

  • Jeon Se-Jin
    • Journal of the Korea Concrete Institute
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    • v.17 no.4
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    • pp.527-533
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    • 2005
  • Axisymmetric modeling of the nuclear containment building has been often employed in practice to estimate structural behavior for the axisymmetric loadings, where the axisymmetric approximation is required for the actual non-axisymmetric tendon arrangements in the dome. In the preceding companion paper, some procedures are proposed for the domestic CANDU and KSNP type containments that can implement the actual 3-dimensional tendon stiffness and prestressing effect into the axisymmetric model. In this paper, the proposed schemes are verified through some numerical examples comparing the results of the actual 3-dimensional model with those of some axisymmetric models. The results of the proposed axisymmetric analyses show relatively good agreements with the actual structural behavior especially for the CANDU type. Also, it is shown that proper level of the prestressing in a hoop direction plays an important role to predict the actual prestressing effect in the axisymmetric dome modeling. Finally, correction factors are discussed that can revise some approximations introduced in the derivations.

A Numerical Simulation for Contractive and Dilative Periodic Motion on Axisymmetric Body

  • Kim, Moon-Chan
    • Journal of Ship and Ocean Technology
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    • v.3 no.1
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    • pp.1-11
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    • 1999
  • Numerical simulation for the axisymmetric body with contractive and dilative periodic motion is carried out. The present analysis shows that a propulsive force can be obtained in highly viscous fluid by the contractive and dilative motion of axisymmetric body. An axisymmetric code is developed with unstructured grid system for the simulation of complicated motion and geometry. It is validated by comparing with the results of Stokes approximation with the problem of uniform flow past a sphere in low Reynolds number($R_n$ = 1). The validated code is applied to the simulation of contractive and dilative periodic motion of body whose results are quantitatively compared with the two dimensional case. The simulation is extended to the analysis of waving surface with projecting part for finding out the difference of hydrodynamics performance according to variation of waving surface configuration. The present study will be the basic research for the development of the propulsor of an axisymmetric micro-hydro-machine.

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Variable-node axisymmetric solid element and its application to adaptive mesh refinement

  • Choi, Chang-Koon;Lee, Eun-Jin;Lee, Wan-Hoon
    • Structural Engineering and Mechanics
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    • v.11 no.4
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    • pp.443-460
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    • 2001
  • This paper presents an effective application of a variable-node axisymmetric solid element designated as AQV (Axisymmetric Quadrilateral Variable-node element). The variable-node element with physical midside nodes helps to overcome some problems in connecting the different layer patterns on a quadrilateral mesh in the adaptive h-refinement. This element alleviates the necessity of imposing displacement constraints on irregular (hanging) nodes in order to enforce the inter-element compatibility. Therefore, the elements with variable mid-side nodes can be used effectively in the local mesh refinement for the axisymmetric structures which have stress concentrations. A modified Gaussian quadrature should be adopted to evaluate the stiffness matrices of the variable-node elements mainly because of the slope discontinuity of assumed displacement within the elements. Some numerical examples show the usefulness of variable-node axisymmetric elements in the practical application.

Radiation in axisymmetric cylindrical coordinates with the modified discrete-ordinates method (축대칭 원통좌표계에서 수정된 구분종좌법에 의한 복사열전달 해석)

  • Kim, Man-Yeong;Baek, Seung-Uk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.2
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    • pp.213-220
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    • 1998
  • The conventional discrete-ordinates method (DOM) is modified and developed for the analysis of two-dimensional axisymmetric cylindrical enclosure with curved wall. The objective of the present work is to extend the capability of the conventional DOM into a general axisymmetric geometry like nozzle-shaped enclosure, by adopting the arbitrary control angle as was done in the finite-volume method (FVM), while keeping the same two-dimensional solution procedure as in the conventional DOM. The present method is validated by applying it to three different benchmark problems of axisymmetric enclosure containing absorbing, emitting and scattering medium. Results presented in this work not only support the solution accuracy, but also moderate efficiency in the numerical calculation of axisymmetric radiation problem.

A Study on the Non-Axisymmetric Closed-Die Ring Forging (비축대칭 형상의 밀폐형 링 단조에 관한 연구)

  • 배원병;김영호;이종헌;이원희
    • Transactions of Materials Processing
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    • v.3 no.2
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    • pp.202-214
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    • 1994
  • An upper bound elemental technique(UBET) is applied to predict the forging load and die-cavity filling for non-axisymmetric ring forging. In order to analyze the process easily, it is suggested that the finial product is divided into three different deformation regions. That is axisymmetric part in corner, lateral plane-strain part and shear deformation on boundaries between them. the place-strain and axisymmetric part are combinded by building block method. Also the total energy is computered through combination of three deformation part. Experiments have been carried out with pure plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agreement with the experimental results.

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